a(n) = Sum_{k=1..n} k!^2.A104344a(n) = Sum_{k=1..n} k!^2.Terms a(0) =1a(1) =5a(2) =41a(3) =617a(4) =15017a(5) =533417a(6) =25935017a(7) =1651637417a(8) =133333531817External referencesoeis: A104344